There is but one part of my conduct in the whole affair on which I do not reflect with satisfaction; it is, that I condescended to adopt the measures of art so far as to conceal from him your sister's being in town. I knew it myself, as it was known to Miss Bingley; but her brother is even yet ignorant of it. That they might have met without ill consequence is perhaps probable; but his regard did not appear to me enough extinguished for him to see her without some danger. Perhaps this concealment, this disguise was beneath me; it is done, however, and it was done for the best. On this subject I have nothing more to say, no other apology to offer. (Chapter 35)

Disguise of every sort is his abhorrence unless it is part of separating his friend from an unhappy connection. I think keeping Bingley in the dark about Jane’s presence in town is disguise of a sort. It might gentle the offense a very little if Darcy had only kept quite about a subject that never came up in conservation but that does not appear to be the situation. Darcy says he did not believe Bingley’s regard enough extinguished for him to see Jane without some danger. This strongly suggests to me that even after Bingley was persuaded to give Jane up he still vocalized about her otherwise how would Darcy know it would be a danger for Bingley to see her? I have pointed out several times that Jane suffers at the hands of Darcy but it appears that Bingley does too. Darcy says “perhaps” doing this was beneath him and offers no apology. I dare to say it was beneath him and he does owe several apologies. (;D) Of course everyone makes mistakes, even those who make it the study of their life “to avoid those weaknesses which often expose a strong understanding to ridicule.” (Chapter 11)